When a token does NOT exist, then `Url::fromUserInput` tries to generate the URL by using the token, it throws:
The user-entered string '' must begin with a '/', '?', or '#'.
Add a token that does NOT apply, for example, a node without parent-parent within the menu system:
[node:menu-link:parent:parent:url]
Add an extra parameter to the token manager in order to clear the text when a token replacement is NOT found.
['clear' => TRUE] then we can confirm the Url is NOT empty before using the `Url::fromUserInput` method.
Fixed
2.0
Code
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#3323183 Fix invalid token "The user-entered string ''